/*

 * Driver for the iTalk binary protocol used by FasTrax

 *

 * Week counters are not limited to 10 bits. It's unknown what

 * the firmware is doing to disambiguate them, if anything; it might just

 * be adding a fixed offset based on a hidden epoch value, in which case

 * unhappy things will occur on the next rollover.

 *

 * This file is Copyright 2010 by the GPSD project

 * SPDX-License-Identifier: BSD-2-clause

 *

 */

#include "../include/gpsd_config.h"  // must be before all includes

#include <math.h>

#include <stdbool.h>

#include <stdio.h>

#include <string.h>

#include <unistd.h>

#include "../include/gpsd.h"

#if defined(ITRAX_ENABLE)

#include "../include/bits.h"

#include "../include/driver_italk.h"

#include "../include/timespec.h"

static gps_mask_t italk_parse(struct gps_device_t *, unsigned char *, size_t);

static gps_mask_t decode_itk_navfix(struct gps_device_t *, unsigned char *,

                                    size_t);

static gps_mask_t decode_itk_prnstatus(struct gps_device_t *, unsigned char *,

                                       size_t);

static gps_mask_t decode_itk_utcionomodel(struct gps_device_t *,

                                          unsigned char *, size_t);

static gps_mask_t decode_itk_subframe(struct gps_device_t *, unsigned char *,

                                      size_t);

// NAVIGATION_MSG, message id 7

static gps_mask_t decode_itk_navfix(struct gps_device_t *session,

                                    unsigned char *buf, size_t len)

{

    unsigned short flags, pflags;

    timespec_t ts_tow;

    uint32_t tow;            // Time of week [ms]

    char ts_buf[TIMESPEC_LEN];

    gps_mask_t mask = 0;

    if (296 != len) {

        GPSD_LOG(LOG_PROG, &session->context->errout,

                 "ITALK: bad NAV_FIX (len %zu, should be 296)\n",

                 len);

        return -1;

    }

    flags = (unsigned short) getleu16(buf, 7 + 4);

    //cflags = (unsigned short) getleu16(buf, 7 + 6);

    pflags = (unsigned short) getleu16(buf, 7 + 8);

    session->newdata.status = STATUS_UNK;

    session->newdata.mode = MODE_NO_FIX;

    mask = ONLINE_SET | MODE_SET | STATUS_SET | CLEAR_IS;

    // just bail out if this fix is not marked valid

    if (0 != (pflags & FIX_FLAG_MASK_INVALID)

        || 0 == (flags & FIXINFO_FLAG_VALID)) {

        return mask;

    }

    tow = getleu32(buf, 7 + 84);   // tow in ms

    MSTOTS(&ts_tow, tow);

    session->newdata.time = gpsd_gpstime_resolv(session,

        (unsigned short) getles16(buf, 7 + 82), ts_tow);

    mask |= TIME_SET | NTPTIME_IS;

    session->newdata.ecef.x = (double)(getles32(buf, 7 + 96) / 100.0);

    session->newdata.ecef.y = (double)(getles32(buf, 7 + 100) / 100.0);

    session->newdata.ecef.z = (double)(getles32(buf, 7 + 104) / 100.0);

    session->newdata.ecef.vx = (double)(getles32(buf, 7 + 186) / 1000.0);

    session->newdata.ecef.vy = (double)(getles32(buf, 7 + 190) / 1000.0);

    session->newdata.ecef.vz = (double)(getles32(buf, 7 + 194) / 1000.0);

    mask |= ECEF_SET | VECEF_SET;

    /* this eph does not look right, badly documented.

     * let gpsd_error_model() handle it

     * session->newdata.eph = (double)(getles32(buf, 7 + 252) / 100.0);

     */

    session->newdata.eps = (double)(getles32(buf, 7 + 254) / 100.0);

    // compute epx/epy in gpsd_error_model(), not here

    mask |= HERR_SET;

#define MAX(a,b) (((a) > (b)) ? (a) : (b))

    session->gpsdata.satellites_used =

        (int)MAX(getleu16(buf, 7 + 12), getleu16(buf, 7 + 14));

    mask |= USED_IS;

    if (flags & FIX_CONV_DOP_VALID) {

        session->gpsdata.dop.hdop = (double)(getleu16(buf, 7 + 56) / 100.0);

        session->gpsdata.dop.gdop = (double)(getleu16(buf, 7 + 58) / 100.0);

        session->gpsdata.dop.pdop = (double)(getleu16(buf, 7 + 60) / 100.0);

        session->gpsdata.dop.vdop = (double)(getleu16(buf, 7 + 62) / 100.0);

        session->gpsdata.dop.tdop = (double)(getleu16(buf, 7 + 64) / 100.0);

        mask |= DOP_SET;

    }

    if (0 == (pflags & FIX_FLAG_MASK_INVALID) &&

        0 != (flags & FIXINFO_FLAG_VALID)) {

        if (pflags & FIX_FLAG_3DFIX) {

            session->newdata.mode = MODE_3D;

        } else {

            session->newdata.mode = MODE_2D;

        }

        if (pflags & FIX_FLAG_DGPS_CORRECTION) {

            session->newdata.status = STATUS_DGPS;

        } else {

            session->newdata.status = STATUS_GPS;

        }

    }

    GPSD_LOG(LOG_DATA, &session->context->errout,

             "NAV_FIX: time=%s, ecef x:%.2f y:%.2f z:%.2f altHAE=%.2f "

             "speed=%.2f track=%.2f climb=%.2f mode=%d status=%d gdop=%.2f "

             "pdop=%.2f hdop=%.2f vdop=%.2f tdop=%.2f\n",

             timespec_str(&session->newdata.time, ts_buf, sizeof(ts_buf)),

             session->newdata.ecef.x,

             session->newdata.ecef.y, session->newdata.ecef.z,

             session->newdata.altHAE, session->newdata.speed,

             session->newdata.track, session->newdata.climb,

             session->newdata.mode, session->newdata.status,

             session->gpsdata.dop.gdop, session->gpsdata.dop.pdop,

             session->gpsdata.dop.hdop, session->gpsdata.dop.vdop,

             session->gpsdata.dop.tdop);

    return mask;

}

static gps_mask_t decode_itk_prnstatus(struct gps_device_t *session,

                                       unsigned char *buf, size_t len)

{

    gps_mask_t mask = 0;

    unsigned int i, nsv, nchan, st;

    uint32_t msec;

    timespec_t ts_tow;

    char ts_buf[TIMESPEC_LEN];

    if (62 > len) {

        GPSD_LOG(LOG_PROG, &session->context->errout,

                 "ITALK: runt PRN_STATUS (len=%zu)\n", len);

        return mask;

    }

    msec = getleu32(buf, 7 + 6);

    MSTOTS(&ts_tow, msec);

    session->gpsdata.skyview_time = gpsd_gpstime_resolv(session,

        (unsigned short)getleu16(buf, 7 + 4), ts_tow);

    gpsd_zero_satellites(&session->gpsdata);

    nchan = (unsigned int)getleu16(buf, 7 + 50);

    if (nchan > MAX_NR_VISIBLE_PRNS) {

        nchan = MAX_NR_VISIBLE_PRNS;

    }

    for (i = st = nsv = 0; i < nchan; i++) {

        unsigned int off = 7 + 52 + 10 * i;

        unsigned short flags;

        bool used;

        flags = (unsigned short) getleu16(buf, off);

        used = (bool)(flags & PRN_FLAG_USE_IN_NAV);

        session->gpsdata.skyview[st].PRN =

            (short)(getleu16(buf, off + 4) & 0xff);

        session->gpsdata.skyview[st].elevation =

            (double)(getles16(buf, off + 6) & 0xff);

        session->gpsdata.skyview[st].azimuth =

            (double)(getles16(buf, off + 8) & 0xff);

        session->gpsdata.skyview[st].ss =

            (double)(getleu16(buf, off + 2) & 0xff);

        session->gpsdata.skyview[st].used = used;

        if (session->gpsdata.skyview[st].PRN > 0) {

            st++;

            if (used) {

                nsv++;

            }

        }

    }

    session->gpsdata.satellites_visible = (int)st;

    session->gpsdata.satellites_used = (int)nsv;

    mask = USED_IS | SATELLITE_SET;

    GPSD_LOG(LOG_DATA, &session->context->errout,

             "PRN_STATUS: time=%s visible=%d used=%d "

             "mask={USED|SATELLITE}\n",

             timespec_str(&session->newdata.time, ts_buf, sizeof(ts_buf)),

             session->gpsdata.satellites_visible,

             session->gpsdata.satellites_used);

    return mask;

}

static gps_mask_t decode_itk_utcionomodel(struct gps_device_t *session,

                                          unsigned char *buf, size_t len)

{

    int leap;

    unsigned short flags;

    timespec_t ts_tow;

    uint32_t tow;            // Time of week [ms]

    char ts_buf[TIMESPEC_LEN];

    if (64 != len) {

        GPSD_LOG(LOG_PROG, &session->context->errout,

                 "ITALK: bad UTC_IONO_MODEL (len %zu, should be 64)\n",

                 len);

        return 0;

    }

    flags = (unsigned short) getleu16(buf, 7);

    if (0 == (flags & UTC_IONO_MODEL_UTCVALID)) {

        return 0;

    }

    leap = (int)getleu16(buf, 7 + 24);

    if (session->context->leap_seconds < leap) {

        session->context->leap_seconds = leap;

    }

    tow = getleu32(buf, 7 + 38);    // in ms

    MSTOTS(&ts_tow, tow);

    session->newdata.time = gpsd_gpstime_resolv(session,

        (unsigned short) getleu16(buf, 7 + 36), ts_tow);

    GPSD_LOG(LOG_DATA, &session->context->errout,

             "UTC_IONO_MODEL: time=%s mask={TIME}\n",

             timespec_str(&session->newdata.time, ts_buf, sizeof(ts_buf)));

    return TIME_SET | NTPTIME_IS;

}

static gps_mask_t decode_itk_subframe(struct gps_device_t *session,

                                      unsigned char *buf, size_t len)

{

    unsigned short flags, prn, sf;

    unsigned int i;

    uint32_t words[10];

    if (64 != len) {

        GPSD_LOG(LOG_PROG, &session->context->errout,

                 "ITALK: bad SUBFRAME (len %zu, should be 64)\n", len);

        return 0;

    }

    flags = (unsigned short) getleu16(buf, 7 + 4);

    prn = (unsigned short) getleu16(buf, 7 + 6);

    sf = (unsigned short) getleu16(buf, 7 + 8);

    GPSD_LOG(LOG_PROG, &session->context->errout,

             "iTalk 50B SUBFRAME prn %u sf %u - decode %s %s\n",

             prn, sf,

             (flags & SUBFRAME_WORD_FLAG_MASK) ? "error" : "ok",

             (flags & SUBFRAME_GPS_PREAMBLE_INVERTED) ? "(inverted)" : "");

    if (flags & SUBFRAME_WORD_FLAG_MASK) {

        return 0;       // don't try decode an erroneous packet

    }

    /*

     * Timo says "SUBRAME message contains decoded navigation message subframe

     * words with parity checking done but parity bits still present."

     */

    for (i = 0; i < 10; i++) {

        words[i] = (uint32_t)(getleu32(buf, 7 + 14 + 4 * i) >> 6) & 0xffffff;

    }

    return gpsd_interpret_subframe(session, GNSSID_GPS, prn, words);

}

static gps_mask_t decode_itk_pseudo(struct gps_device_t *session,

                                      unsigned char *buf, size_t len)

{

    unsigned short flags, n, i;

    unsigned int tow;             // time of week, in ms

    timespec_t ts_tow;

    n = (unsigned short) getleu16(buf, 7 + 4);

    if (1 > n ||

        MAXCHANNELS < n ) {

        GPSD_LOG(LOG_INF, &session->context->errout,

                 "ITALK: bad PSEUDO channel count\n");

        return 0;

    }

    if (len != (size_t)((n+1)*36)) {

        GPSD_LOG(LOG_PROG, &session->context->errout,

                 "ITALK: bad PSEUDO len %zu\n", len);

    }

    GPSD_LOG(LOG_PROG, &session->context->errout, "iTalk PSEUDO [%u]\n", n);

    flags = (unsigned short)getleu16(buf, 7 + 6);

    if ((flags & 0x3) != 0x3) {

        return 0; // bail if measurement time not valid.

    }

    tow = (unsigned int)getleu32(buf, 7 + 38);

    MSTOTS(&ts_tow, tow);

    session->newdata.time = gpsd_gpstime_resolv(session,

        (unsigned short int)getleu16((char *)buf, 7 + 8), ts_tow);

    session->gpsdata.raw.mtime = session->newdata.time;

    // this is so we can tell which never got set

    for (i = 0; i < MAXCHANNELS; i++) {

        session->gpsdata.raw.meas[i].svid = 0;

    }

    for (i = 0; i < n; i++){

        session->gpsdata.skyview[i].PRN =

            getleu16(buf, 7 + 26 + (i*36)) & 0xff;

        session->gpsdata.skyview[i].ss =

            getleu16(buf, 7 + 26 + (i*36 + 2)) & 0x3f;

        session->gpsdata.raw.meas[i].satstat =

            getleu32(buf, 7 + 26 + (i*36 + 4));

        session->gpsdata.raw.meas[i].pseudorange =

            getled64((char *)buf, 7 + 26 + (i*36 + 8));

        session->gpsdata.raw.meas[i].doppler =

            getled64((char *)buf, 7 + 26 + (i*36 + 16));

        session->gpsdata.raw.meas[i].carrierphase =

            getleu16(buf, 7 + 26 + (i*36 + 28));

        session->gpsdata.raw.meas[i].codephase = NAN;

        session->gpsdata.raw.meas[i].deltarange = NAN;

    }

    // return RAW_IS; The above decode does not give reasonable results

    return 0;         // do not report valid until decode is fixed

}

static gps_mask_t italk_parse(struct gps_device_t *session,

                              unsigned char *buf, size_t len)

{

    unsigned int type;

    gps_mask_t mask = 0;

    if (0 == len) {

        return 0;

    }

    type = (unsigned int) getub(buf, 4);

    // we may need to dump the raw packet

    GPSD_LOG(LOG_RAW, &session->context->errout,

             "raw italk packet type 0x%02x\n", type);

    session->cycle_end_reliable = true;

    switch (type) {

    case ITALK_NAV_FIX:

        GPSD_LOG(LOG_DATA, &session->context->errout,

                 "iTalk NAV_FIX len %zu\n", len);

        mask = decode_itk_navfix(session, buf, len) | (CLEAR_IS | REPORT_IS);

        break;

    case ITALK_PRN_STATUS:

        GPSD_LOG(LOG_DATA, &session->context->errout,

                 "iTalk PRN_STATUS len %zu\n", len);

        mask = decode_itk_prnstatus(session, buf, len);

        break;

    case ITALK_UTC_IONO_MODEL:

        GPSD_LOG(LOG_DATA, &session->context->errout,

                 "iTalk UTC_IONO_MODEL len %zu\n", len);

        mask = decode_itk_utcionomodel(session, buf, len);

        break;

    case ITALK_ACQ_DATA:

        GPSD_LOG(LOG_DATA, &session->context->errout,

                 "iTalk ACQ_DATA len %zu\n", len);

        break;

    case ITALK_TRACK:

        GPSD_LOG(LOG_DATA, &session->context->errout,

                 "iTalk TRACK len %zu\n", len);

        break;

    case ITALK_PSEUDO:

        GPSD_LOG(LOG_DATA, &session->context->errout,

                 "iTalk PSEUDO len %zu\n", len);

        mask = decode_itk_pseudo(session, buf, len);

        break;

    case ITALK_RAW_ALMANAC:

        GPSD_LOG(LOG_DATA, &session->context->errout,

                 "iTalk RAW_ALMANAC len %zu\n", len);

        break;

    case ITALK_RAW_EPHEMERIS:

        GPSD_LOG(LOG_DATA, &session->context->errout,

                 "iTalk RAW_EPHEMERIS len %zu\n", len);

        break;

    case ITALK_SUBFRAME:

        mask = decode_itk_subframe(session, buf, len);

        break;

    case ITALK_BIT_STREAM:

        GPSD_LOG(LOG_DATA, &session->context->errout,

                 "iTalk BIT_STREAM len %zu\n", len);

        break;

    case ITALK_AGC:

    case ITALK_SV_HEALTH:

    case ITALK_PRN_PRED:

    case ITALK_FREQ_PRED:

    case ITALK_DBGTRACE:

    case ITALK_START:

    case ITALK_STOP:

    case ITALK_SLEEP:

    case ITALK_STATUS:

    case ITALK_ITALK_CONF:

    case ITALK_SYSINFO:

    case ITALK_ITALK_TASK_ROUTE:

    case ITALK_PARAM_CTRL:

    case ITALK_PARAMS_CHANGED:

    case ITALK_START_COMPLETED:

    case ITALK_STOP_COMPLETED:

    case ITALK_LOG_CMD:

    case ITALK_SYSTEM_START:

    case ITALK_STOP_SEARCH:

    case ITALK_SEARCH:

    case ITALK_PRED_SEARCH:

    case ITALK_SEARCH_DONE:

    case ITALK_TRACK_DROP:

    case ITALK_TRACK_STATUS:

    case ITALK_HANDOVER_DATA:

    case ITALK_CORE_SYNC:

    case ITALK_WAAS_RAWDATA:

    case ITALK_ASSISTANCE:

    case ITALK_PULL_FIX:

    case ITALK_MEMCTRL:

    case ITALK_STOP_TASK:

        GPSD_LOG(LOG_DATA, &session->context->errout,

                 "iTalk not processing packet: id 0x%02x length %zu\n",

                 type, len);

        break;

    default:

        GPSD_LOG(LOG_DATA, &session->context->errout,

                 "iTalk unknown packet: id 0x%02x length %zu\n",

                 type, len);

    }

    return mask | ONLINE_SET;

}

static gps_mask_t italk_parse_input(struct gps_device_t *session)

{

    if (ITALK_PACKET == session->lexer.type) {

        return italk_parse(session, session->lexer.outbuffer,

                           session->lexer.outbuflen);

    }

    if (NMEA_PACKET == session->lexer.type) {

        return nmea_parse((char *)session->lexer.outbuffer, session);

    }

    return 0;

}

#ifdef __UNUSED__

// send a "ping". it may help us detect an itrax more quickly

static void italk_ping(struct gps_device_t *session)

{

    char *ping = "<?>";

    (void)gpsd_write(session, ping, 3);

}

#endif  // __UNUSED__

// *INDENT-OFF*

const struct gps_type_t driver_italk =

{

    .type_name      = "iTalk",          // full name of type

    .packet_type    = ITALK_PACKET,     // associated lexer packet type

    .flags          = DRIVER_STICKY,    // no rollover or other flags

    .trigger        = NULL,             // recognize the type

    .channels       = 12,               // consumer-grade GPS

    .probe_detect   = NULL,             // how to detect at startup time

    .get_packet     = packet_get1,      // use generic packet grabber

    .parse_packet   = italk_parse_input,// parse message packets

    .rtcm_writer    = gpsd_write,       // send RTCM data straight

    .init_query     = NULL,             // non-perturbing initial query

    .event_hook     = NULL,             // lifetime event handler

    .speed_switcher = NULL,             // no speed switcher

    .mode_switcher  = NULL,             // no mode switcher

    .rate_switcher  = NULL,             // no sample-rate switcher

    .min_cycle.tv_sec  = 1,             // not relevant, no rate switch

    .min_cycle.tv_nsec = 0,             // not relevant, no rate switch

    .control_send   = NULL,             // no control string sender

    .time_offset     = NULL,            // no method for NTP fudge factor

};

// *INDENT-ON*

#endif  // defined(ITRAX_ENABLE)

// vim: set expandtab shiftwidth=4